I have a small blister behind my crooked wisdom tooth but it doesn't hurt at all,I don't even feel that is there.I can see it when I open my mouth though,and when I tried to press it ,it was very soft and it also contains a little bit blood.I feel little pain only when I press hard on it.I can eat,open my mouth,and talk without any problems because as I said it doesn't hurt and I don't feel it. What could that mean,and do I need an extraction to my wisdom tooth even if it doesn't annoy me?